Conductive contacts are formed to electrically connect various semiconductor devices (e.g., source/drain regions of metal oxide semiconductor field effect transistors (MOSFETs) or MOS transistors) of integrated circuits (ICs). The contacts are conventionally formed by patterning and etching a dielectric material layer to form a contact opening, depositing a liner/barrier layer, typically a combination of layers, such as titanium (Ti), tantalum (Ta), ruthenium (Ru), titanium nitride (TiN), tantalum nitride (TaN), tungsten nitride (WN), and/or cobalt (Co) to line the side surfaces and bottom of the contact opening, and depositing a conductive material, such as tungsten (W) or copper (Cu) to fill the contact opening. The liner-barrier prevents diffusion of the conductive material into the dielectric material layer and enhances adhesion of the conductive material to the walls of the contact opening.
An example of typical electrical connections formed by contacts is between a semiconductor device in a device region of the IC and a metallization layer (e.g., bottom metallization layer disposed above the device region commonly referred to as a M1 layer). The contact is electrically connected at one end to the semiconductor device as described above by forming the contact opening through the dielectric material layer to the device region and depositing the liner/barrier layer and conductive material. Similarly, the contact is electrically connected at the other end to the metallization layer by depositing a second dielectric material layer overlying the contact and the first dielectric material layer, forming a metallization trench to expose the contact, and subsequently depositing a liner/barrier layer and a metallization layer (e.g., copper (Cu)) to fill the metallization trench.
As feature sizes decrease from 150 nanometers (nm) to 90 nm, then to 45 nm and below (e.g., 32 nm, 20 nm, and below), the aspect ratio (e.g., height to diameter/width) of contacts and their corresponding contact openings substantially increase. As such, filling the contact openings with conductive material can be more challenging and lead to poor fill with large seam voids and higher resistance. Additionally, it has been found that when such ICs are electrically stressed, the metallization layer can undesirably breakthrough the liner/barrier layer above a large seam void and diffuse through the contact to the contact-device region interface which can impact the reliability of the IC.
Accordingly, it is desirable to provide integrated circuits having device contacts with improved robustness and methods for fabricating such integrated circuits. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.